1. Field of Invention
This invention relates to inspection methods and systems for machine vision applications.
2. Description of Background Information
There are various techniques for inspecting various types of manufactured objects. In such inspections, a determination may be made as to whether the object has certain featuresxe2x80x94present before or after a given manufacturing step. For example, during manufacturing of continuous web products, such as paper, metals, plastic foils and non-woven materials, the visual quality of the product or product surface may be monitored.
An existing approach for inspection of such products is based on optical measurement using a light source or multiple light sources to illuminate a material to be inspected and a camera to sense visible characteristics of the material to be inspected, such as material integrity or grade of the material. In such systems, camera elements are typically exposed to light transmitted through the continuous web of material or reflected from the surface of the material. In some of these systems, a number of filters may be mechanically switched to adjust or control the exposure control of the camera, which are sometimes referred to as xe2x80x9cfilter flippersxe2x80x9d or xe2x80x9clight attenuatorsxe2x80x9d.
Existing inspection approaches change the light source or control the light intensity by adjusting the output level in line scan cameras or the pulse duration in matrix cameras.
An exemplary embodiment of the invention provides A machine vision method and system for inspecting a material. The system comprises a light source arranged to illuminate the material and an imaging device configured to acquire image data corresponding to at least one characteristic of the material while the material is being illuminated by the light source. An image processor is configured to normalize the image data and to control adjustment of an exposure control level for the imaging device based upon the normalized image data.
An exemplary method of implementing the machine vision system may include illuminating a material using a light source and obtaining image data corresponding to the material using an imaging device. The image data is normalized and the adjustment of an exposure control level of the imaging device is controlled based on the raw data.